{"nrhp_refnum":"96000099","name":"Ostheimer, Martha and Maurice, Estate","other_names":["Grimmet","see also:Wee Grimmet(West Whiteland Township MRA)"],"category":"building","location":{"address":"620 W. Lincoln Hwy., West Whiteland Township","address_restricted":false,"city":"Exton","county":"Chester County","state":"PA","lat":40.02031321700008,"lon":-75.66203120799997,"geom_source":"nps_gis"},"listed_date":"1996-02-16","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Architecture"],"significance_levels":["state"],"summary":{"what_it_is":"Grimmet, a Tudor Revival house of brown sandstone on a 6.9-acre estate on the south side of Pennsylvania Route 30 in West Whiteland Township, Chester County, near Exton, built in 1924 and enlarged in 1952, with the adjoining ca. 1820 stone quarryman's house Wee Grimmet, a stone arch bridge, designed landscape features and a former quarry site.","why_significant":"The nomination argues Grimmet is a significant part of West Whiteland Township's 20th century architecture and an excellent example of the work of architect John Gilbert McIlvaine. It states the house retains strong integrity and reflects the Tudor Revival style and the affluence of the early 1920s. The property is also presented as conveying its use as an early 20th century gentleman's farm and its evolution from a 19th century quarry estate.","narrative":"Grimmet is a large Tudor Revival house of brown sandstone set back from Route 30 in West Whiteland Township, Chester County. Architect John Gilbert McIlvaine designed it in 1924 for Dr. Maurice Ostheimer, an orthopedic surgeon at the University of Pennsylvania, and his wife Martha McIlvain Ostheimer, who bought the 38.5-acre farm in 1923. Its many gables, oriel bay window and iron casement windows reflect the period's English-inspired design. A 1952 enlargement by the family added a service wing and garage in matching materials and style. The interior has oak beams, hand-wrought iron stair standards, and a cast stone fireplace depicting the McIlvaine family's crossing to Pennsylvania. The property is significant as an excellent example of McIlvaine's work, which the nomination places among the finest country houses in the Philadelphia area. Its designed landscape, terraces and circular pools, along with the adjacent quarryman's house, convey an early twentieth-century rural estate.","period_of_significance":"1924- ca. 1935","architect_builder":"John Gilbert McIlvaine (architect)","architectural_style":"20th century revivals/renaisance","criteria":["C"],"status_note":"Grimmet is now used as offices of Resource Strategies, Inc.; the gardens have largely reverted to grass and the house is described as having been unchanged internally for that use.","vacant_flag":false,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:36.337771-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/96000099.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/96000099/36933becc2-800.webp","url_1600":"https://nationalhistoricalregister.com/media/96000099/36933becc2-1600.webp","licence":"Public domain","author":"Smallbones","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Osterheimer_Chesco.JPG\" rel=\"noopener\">Smallbones</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Osterheimer_Chesco.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71995569","wikipedia":"https://en.wikipedia.org/wiki/Martha_and_Maurice_Ostheimer_Estate","wikidata":"https://www.wikidata.org/wiki/Q6774625"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/chester-county/ostheimer-martha-and-maurice-estate-96000099/"}